Putters are well known and include a putter head having a front strike face. Putters typically have an intended contact region centrally positioned on the strike face and commonly referred to as the “sweet spot.” The intended contact region is often generally indicated by a sight line that rearwardly extends from the strike face at an angle perpendicular to the strike face. When a user contacts a golf ball with the putter at the intended contact region of the strike face, the putter typically generates an amount of audible and vibrational energy that provides the user with sound indicative of solid contact with a ball and a corresponding “good feel.” Most importantly, the ball, upon contact with the intended contact region of the strike face, will typically and consistently travel a distance that is directly proportional to the speed of the putter head at impact.
Conversely, when a user contacts the golf ball at a position away from the intended contact region, commonly referred to as a “mis-hit,” the ball will typically travel a distance that is significantly less than that of a ball contacted at the intended contact region of the strike face. Moreover, the distance loss can be variable and unpredictable. In an effort to increase the size of the sweet spot of a putter, many putter heads are configured with an increased toe and heel weighting, which increases the putter head's moment of inertia. A putter head with an increased moment of inertia is more resistant to twisting during a mis-hit and, therefore, enables the performance of a mis-hit ball to more closely match the performance of a ball contacted at the sweet spot. However, increased toe and heel weighting alone generally does not eliminate the distance loss that typically occurs during off-center hits.
In efforts to improve the feel of a putter upon impact, many putters include an insert, typically of uniform thickness, mounted into the strike face and/or within the putter head. Such inserts are typically made of a material that is softer than the material of the putter head. Although such soft inserts provide a more desirable softer feel to the user upon impact with a ball, such inserts also typically substantially deaden the sound produced upon impact with the ball making it difficult for the user to measure his or her putting stroke using audible feedback from the putter. Moreover, inserts of uniform thickness typically do not increase the size of the sweet spot or otherwise improve the putter's performance during mis-hits.
Although putters having inserts of varying thickness or depth are known, such inserts are typically connected to the putter head with an adhesive agent that does not allow for uniform direct contact between the insert and the putter head. Moreover, it is not uncommon for adhesives to be unevenly applied or positioned between the insert and the putter head, due to normal manufacturing tolerances. The uneven application of adhesive can result in the development of gaps in random locations throughout the connection region of the insert to putter head. Further, excessively thin, or excessively thick, layers of adhesive can result in the formation of “dead spots” and/or “hot spots” randomly positioned on the strike face of the putter head. Such dead spots and/or hot spots can detrimentally affect the performance of the putter, and severely hinder a user's ability to hit a ball a consistent distance and to develop a feel for the putter. Further, one type of existing putter having an insert of varying thickness also has an exposed upper surface in addition to an exposed front surface. The exposed surfaces of the insert make the insert more susceptible to damage or dislocation from the putter head particularly during insertion and removal of the putter from a golf bag. Additionally, another known putter having an insert of varying thickness also includes multiple pieces inserted into the putter head with no one single insert extending over the entire intended strike region of the strike face. Such a putter is difficult to produce and fails to meet the U.S. Golf Association's requirements for putters.
Thus, there is a continuing need for a putter including an insert of varying rearward depth or thickness that increases the size of the putter's sweet spot thereby improving the putter's performance in response to a mis-hit. There is also a continuing need for a putter having an insert of variable thickness that does not include gaps, hot spots or dead spots over the area connecting the insert to the putter head. What is also needed is a putter with an insert of varying thickness that does not produce a deadened sound upon impact with a golf ball. Moreover, it would be advantageous to provide a putter having an insert that is protected from damage or dislocation during use. It would also be advantageous to provide a putter with an insert of varying thickness that satisfies the U.S. Golf Association's requirements for putters.